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Abstract:

A restraint system for a motor vehicle unfolds from a storage position to
a restraint position. The unfolding is carried out by at least one
supporting structure that can be inflated by a gas pressure source; and
in the restraining position, the occupant is provided with a carrier
volume for restraining the occupant in the displacement position, whereby
the carrier volume is enclosed by at least one carrier structure. The
dimension of the restraint system is adapted to the respective load
condition, and the flexible carrier structure is fixed for enclosing the
carrier volume by inflating the supporting structure.

Claims:

1.-18. (canceled)

19. A restraint system for a motor vehicle that unfolds from a storage
position into a restraining position, wherein: the restraint system is
unfolded by at least one supporting structure that can be inflated by a
gas pressure source, such that, in the restraining position, the occupant
is provided with a carrier volume for restraining the occupant; the
carrier volume is enclosed by at least one flexible carrier structure;
and the flexible carrier structure is fixed for enclosing the carrier
volume by inflating the supporting structure.

20. The restraint system according to claim 19, wherein the longitudinal
extension of the supporting structure significantly exceeds its
transverse extension in the active state.

21. The restraint system according to claim 20, wherein the supporting
structure is filled as a pilot tube which is initially filled after the
activation.

22. The restraint system according to claim 21, wherein the pilot tube is
arranged in overlap with a set break line below an air bag cover.

23. The restraint system according to claim 19, wherein venting or inflow
apertures are provided.

24. The restraint system according to claim 23, wherein the venting or
inflow apertures comprise a variable cross section which can be adjusted
dependent on a degree of unfolding of the supporting structure.

25. The restraint system according to claim 23, wherein venting holes are
directed towards the occupant, and are situated such that they are
covered by an occupant who is displaced in a forward direction.

26. The restraint system according to claim 23, wherein the venting
apertures are perforations or other passages, which are included in
flexible carrier structures enclosing the carrier volume.

27. The restraint system according to claim 19, wherein the storage
position is in a roof region of the vehicle.

28. The restraint system according to claim 19, wherein the carrier
volume can be activated again after a first activation.

29. The restraint system according to claim 19, comprising a plurality of
supporting structures, one of which extends with an at least partial
overlap of a hard structure of the motor vehicle.

30. The restraint system according to claim 19, wherein at least one of
said at least one supporting structures unfolds between the occupants as
an interaction bag.

31. The restraint system according to claim 19, wherein the at least one
supporting structures and the flexible carrier structure are produced in
a one-piece-woven structure.

32. The restraint system according to claim 19, further comprising a
redistribution element for distributing excess gas.

33. The restraint system according to claim 32, wherein the
redistribution means redirects the excess gas into an adjacent supporting
structure.

34. The restraint system according to claim 32, wherein the
redistribution means increases the cross section of the supporting
structure when the interior pressure is too high.

35. The restraint system according to claim 32, wherein the
redistribution means is a pressure-relief valve, through which the excess
gas escapes to the environment or to adjacent supporting structures.

36. The restraint system according to claim 19, further comprising a
heating device which heats or supplements aspired or enclosed gas in the
activated state of the supporting structures.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is related to co-pending U.S. patent application
Ser. No. ______, filed on the same date.

[0003] The present invention relates to a restraint system for a motor
vehicle.

[0004] Inflatable restraint systems such as driver or passenger air bags
are well-known in series-production of vehicles. In a storage position
the air bag is folded, and when an accident is detected, it is filled
with gas in a pyrotechnical manner, so that it abruptly unfolds towards
an occupant who is being displaced in a forward direction. For this
purpose, it is important that the air bag quickly reaches its effective
volume, and it is therefore necessary to produce relative large amounts
of gas (e.g., in a pyrotechnical manner) and to introduce them into the
gas bag. Recently, for dimensioning the gas volume to be added,
occupant/and or vehicle parameters have been evaluated, so as not to
unfold the gas bag to its full size for example with a so-called "out of
position" of the occupant. However, the necessity for adjustment to all
possible load conditions and the relatively cost-intensive control and
regulation technique have made this feature problematic.

[0005] Intensified efforts have been made, therefore, to develop so-called
self-regulating systems which can adjust automatically to the
corresponding load conditions.

[0006] German patent document DE 2 302 737 discloses a restraint system
comprising a two-layer gas bag, where the gas is guided only between the
two layers, so that a complete gas cushion does not result; rather, a
spherical annular support structure. The unfolding of the support
structure thereby occurs in the transverse direction of the abutting gas
cushions. On the other hand, European patent document EP 0589 059 B1
shows furthermore, that it is necessary during the unfolding of the
two-layer gas bag to suck ambient air into the interior to overcome the
negative pressure.

[0007] Both of these systems have in common the feature that less gas
volume is necessary to unfold the gas bag to its full size, due to the
gas bag's formed in a double layer. The temperature and the pollution can
thereby be reduced.

[0008] Finally, UK patent document GB 1 420 226 A discloses a restraint
system for a motor vehicle where a tubular supporting structure is
provided in the interior of the two-layer gas cushion, the longitudinal
extension of which exceeds the dimensions of the transverse extension in
the inflated (that is, active) state. The supporting structure unfolds
due to its particular geometry mainly in the direction of its
longitudinal extension.

[0009] An automatic adjustment of the gas bag dependent on the respective
load condition (e.g., dependent on the respective occupant or his or her
position) is thereby not described.

[0010] It is therefore an object of the present invention to improve the
generic restraint system in such a manner that its size is adjusted to
the respective load condition.

[0011] This and other objects and advantages are achieved by the restraint
system according to the invention, in which one or more supporting
structures can be unfolded by filling them with gas from a gas pressure
source, while restraint is ensured by a carrier volume enclosed by
flexible carrier structures. When the restraint system is activated, only
the supporting structures are filled with gas (for example in a
pyrotechnical manner). During the unfolding or erection of the supporting
structures, flexible carrier structures are fixed, which enclose a
carrier volume that is formed by aspiration of ambient air due to the
fast unfolding of the system, and is sufficient to restrain the occupant.

[0012] As used herein, the term "supporting structure" refers to a
structure similar to a skeleton or a supporting frame-like structure,
which achieves a restraint effect in the fully unfolded state which is
comparable to that of a conventional gas bag, but which has a
considerably more complex structure, for example a branched tree
structure. Thereby, not only the necessary gas volume can be reduced, but
also the force peaks acting on the occupant during unfolding, if he or
she is effectively "in the way" of the unfolding supporting structure. In
contrast, the gas amount in the conventional gas bag is on a
substantially higher level from the start of the activation until the
full unfolding, so that obstacles the unfolding path are put under more
pressure independent of the unfolding state.

[0013] Furthermore, as used herein, the term "flexible carrier structure"
refers to a structure which connects the supporting structures amongst
each other. The carrier structure may be, for example, an air bag fabric,
a net or a similar flexible sheet.

[0014] One advantage of the present invention is that gas from a gas
pressure source need only to be made available for filling the supporting
structures. The gas amount and the load on the occupant can thereby be
reduced considerably. Further, it has been shown that the supporting
structures can also be stopped during the unfolding due to the low gas
volume. That is, the unfolding of the affected structure can be stopped
or hindered more easily by an "out of position" occupant, without
straining him or her excessively, while other supporting structures can
unfold further, so that the flexible carrier structures are fixed and
thus the carrier volume can still be developed in such a manner that a
restraining action takes place.

[0015] If the longitudinal extension of the supporting structure in the
active state considerably exceeds the dimensions of its transverse
direction, a supporting structure is provided, which is in an essentially
tubular form. The reduced cross section of the tubular form can reduce
the force on the occupant at a constant pressure, due to the physical law
pressure=force/area. The supporting structure can thus be stopped by low
forces during unfolding, which can for example take place by bending. Due
to the particular geometric form of the supporting structure (that is,
due to its longitudinal extension which extends its cross section), the
stability and/or the final volume or the final extension which it would
have with a complete unfolding is not achieved when it impacts upon an
obstacle. The supporting structure has a different stability during the
unfolding due to its longitudinal formation. While the supporting
structure is initially rather unstable (that is, it can easily be impeded
during unfolding), the completely unfolded supporting structure still
achieves full stability. This means that, if the supporting structure
impacts upon an obstacle during the unfolding, (as is the case for
example with an occupant who is leaning forward, "out of position"), the
unfolding can be stopped or deflected due to the supporting structure
which is still unstable. These small forces effect a lower pressurization
of the occupant.

[0016] A supporting structure can preferably be formed as a pilot tube,
which is initially filled with the gas from the gas pressure source after
the activation. This means that this pilot tube can be used to open the
air bag flap in a specific manner. The pilot tube does not necessarily
have to be tubular. It can also have the form of e.g., a tetrahedron.

[0017] The pilot tube is preferably in overlap with a set break
line/location below the air bag cover. When the pilot tube is filled, its
cross section abruptly increases in a region that is limited, but which
is very effective towards the opening, so that the air bag flap can be
pressed open with less gas and the restraint system can escape. Thus less
energy is necessary for opening the flap. The load can be lowered.

[0018] In a further embodiment of the invention, venting and/or inflow
apertures can be provided in the restraint system, which enable the
inflow of ambient air or the venting depending on the load condition.

[0019] If the venting and/or inflow apertures comprise a variable cross
section which can be adjusted dependent on the unfolding degree of the
supporting structure, the restraint system can be formed in a
self-regulating manner. That is, the cross section of the venting and/or
the inflow apertures adjusts itself over the extension of the restraint
system, depending on the load condition. The opening cross section can
for example be opened or closed by means of a slider, the more the
supporting structure unfolds for example. The connection between the
slider and the supporting structures can for example take place via
linkages or rebound straps.

[0020] With conventional compact gas bags, it was previously necessary to
refrain from directing venting apertures towards the occupant, because
gas temperatures are reached which are too high. However, with the system
according to the invention, cold ambient air flows within the carrier
volume, and not pyrotechnically produced gas, and venting apertures can
be directed towards the occupant due to the reduced temperature. The air
bag dampening can thus be adapted for various environmental conditions,
by sealing a venting aperture cross section by the occupant with a
different contact surface between occupant and air bag.

[0021] Thus, this contact surface and its sealing with persons having a
higher volume (and usually a higher weight) is larger, so that a stronger
restraint action is achieved hereby. With more severe accidents, the
contact surface and thus the restraint action is also increased by a
stronger immersion of the occupant into the air bag. This principle also
permits a variable air bag dampening for belted and unbelted occupants,
because the occupant in the unbelted state will be immersed into the air
bag with less force.

[0022] If the venting apertures are formed as perforations (that is, many
small apertures), as for example with a textile net, a projection area
corresponding to the measurements of the occupant can be closed. The
reproducibility of the results increases on average with many small
venting apertures.

[0023] In order to produce the gas necessary for the supporting
structures, a gas pressure source, in particular a gas generator, with
only small dimensions is necessary, so that the restraint system can be
stored in the roof region in a storage position. The air bags usually
stored in the steering wheel or in the cockpit region could then be
omitted in favor of restraint systems, which can be stored in the roof
frame region in a space-saving manner and which unfold obliquely from
above towards the direction of the occupant. It would be advantageous
that, with this arrangement, driver and passenger air bags do not have to
differ. Restraint systems which are identical in construction could be
provided for the driver and for the passenger or even occupants of the
rear passenger compartment.

[0024] It is also possible to reactivate the carrier volume again after a
first activation, in that the supporting structure is for example
designed/sealed in such a manner that it keeps its interior pressure for
a longer time (more than 100 ms), so that it can erect at least partially
during load relief. Thus a carrier volume results from the renewed
aspiration of ambient air. This is advantageous for the occupants for a
possible follow-up impact.

[0025] In a preferred embodiment, at least one of the supporting
structures extends at least partially in overlap with a hard structure,
as for example a supporting column. It is also possible to provide a
structure which unfolds between the occupants as an interaction bag.

[0026] To manufacture a complex supporting structure with its inflatable
components and the flexible sheets, the one-piece woven technique is
recommended. This technique distinguishes itself in that, on one and the
same structure, a double layer can be manufactured for the inflatable
structures, and one layer for the flexible sheets, or a three-dimensional
structure can be woven.

[0027] If a supporting structure impacts upon an obstacle during
unfolding, the gas flowing into the supporting structure can be
distributed to other adjacent supporting structures or into the
environment with the aid of redistribution elements. It is also possible
to reduce the inner pressure in the supporting structure generated by the
flow, by increasing the cross section. This can be done in such a manner
that tear seams break down at a certain pressure, so that the supporting
structure can increase in its transverse direction. A pressure-relief
valve, which opens when an interior pressure is reached which is too
high, can also be used.

[0028] If several supporting structures are connected to one another by
the flexible carrier structures, in particular sheets, the gas can be
used for restraining action in the carrier volume enclosed by the carrier
structure. The gas in the carrier volume, which serves to restrain
occupants, can be heated or supplemented by means of a heating device
(e.g., an ignition tablet or a small gas generator step, which develops
heat and possibly a low gas volume). The gas volume or the inner pressure
and thus the restraint action increases therewith correspondingly.

[0029] Other objects, advantages and novel features of the present
invention will become apparent from the following detailed description of
the invention when considered in conjunction with the accompanying
drawings.

[0031] FIG. 2a shows the obstruction of the unfolding of the supporting
structure according to FIG. 1 when it impacts upon an obstacle;

[0032]FIG. 2b shows an evasion of the supporting structure according to
FIG. 1 when impacting upon an obstacle 1;

[0033]FIG. 3 shows the supporting structure according to FIG. 1 in the
fully unfolded state;

[0034]FIG. 4 shows a restraint system with a complex supporting
structure;

[0035]FIG. 5 shows the restraint system according to FIG. 4 when
impacting upon an obstacle;

[0036]FIG. 6 shows a restraint system in a further embodiment with a
complex supporting structure that includes two supporting structures
connected to one another by a flexible sheet; and

[0037] FIG. 7 shows the restraint system according to FIG. 6 when
impacting upon an obstacle.

DETAILED DESCRIPTION OF THE DRAWINGS

[0038] FIGS. 1 to 3 show a supporting structure 1 in a schematic side
view, which is rolled up in the deactivated state. Alternatively, a
zigzag folding or other foldings are possible. As can be seen especially
from FIG. 3, the length L of the supporting structure in the fully
extended active or deployed state substantially exceeds the dimensions of
the cross section Q. It is thereby unimportant which form of cross
section the supporting structure 1 comprises. If a gas generator assigned
to the supporting structure 1 is activated by inflation, the abruptly
generated gas G reaches the interior 3 of the supporting structure 1
formed by walls 2.

[0039] If an obstacle 5 is present in the unfolding path, the portion 4
that is not yet unfolded due to the low cross section is disconnected, so
that no further G can flow in (see FIG. 2a). The supporting structure 1
is markedly unstable in relation to interfering transverse forces in this
state, so that the portion not yet unfolded is simply disconnected at the
location 6 when an obstacle is impacted. The supporting structure thereby
does not achieve the stability which it would have when fully unfolded
and/or the end volume or the final extension, and the load values on the
occupants are thus reduced substantially.

[0040] Depending on the impact angle between the obstacle 5 and the
supporting structure 1, an evasion of the supporting structure can take
place instead of the complete disconnection (see FIG. 2b). The supporting
structure also does not achieve the stability which it would have when
fully unfolded.

[0041] If the supporting structure 1 is however completely filled with gas
(FIG. 3), full stability is achieved.

[0042] FIGS. 1 to 3 show the principal mode of operation of an individual
supporting structure. The restraint system develops its full restraint
effect only in cooperation with flexible carrier structures. This is
explained in the following by means of FIGS. 4 to 7.

[0043]FIG. 4 shows a restraint system 8 in its restraint (deployed)
position. It includes several supporting structures 1, with several
flexible carrier structures 7 connecting them. The restraint system 8 has
unfolded from its storage position in the cockpit 9 towards an occupant
10. Supporting structures 11 are provided, which are fluidically
connected to one another via transverse supporting structures 12.
Flexible carrier structures 7 (in particular flexible sheets) are fixed
between the supporting structures 11 and 12. The flexible carrier
structures 7 enclose thereby a carrier volume 13 (which is cuboidal in
this case). It is obvious that the outer form of the carrier volume 13 is
dependent on the spatial course of the supporting structures and the
carrier structures.

[0044] During unfolding of the restraint system 8, the supporting
structures 11 are first filled with gas, so that they are erected and
that the gas can also flow into the transverse supporting structures 12
according to the arrow direction G. The flexible carrier structures 7 are
thereby fixed between the supporting structures 11, 12 and the carrier
volume 13 is enclosed. The ambient air necessary for the restraining
action is aspired into the interior of the restraint system 8 by
corresponding inflow apertures. The negative pressure resulting in the
interior of the restraint system 8 effects a fast aspiration of ambient
air, so that an additional pressure source is not necessary. If the
interior pressure should still be too low, the gas can be heated or
supplemented by means of a heating device (e.g., an ignition tablet or a
small gas generator step, which generates heat and possibly a low gas
volume), so that the gas expands abruptly and the inner pressure thus
increases.

[0045] If the unfolding restraint system 8 impacts upon an obstacle 5, for
example an "out of position" occupant, the unfolding of the supporting
structures 11 is obstructed by pinching off or bending. Nevertheless, a
carrier volume 13 is enclosed by at least partial fixing of the carrier
structures 7, which brings about a corresponding restraint action.

[0046] A second embodiment is shown in FIG. 6. The same reference numerals
indicate the same components. Differing embodiments are characterized by
an apostrophe.

[0047] The supporting structures 11' are filled with gas from a gas
pressure source according to the arrow direction G. The gas flows from
the supporting structures 11' into the transverse supporting structures
12'. The flexible carrier structures 7' are fixed again by the erection
of the supporting structures 11', 12', so that the carrier volume 13'
results. The supporting structures 11' projecting beyond the transverse
supporting structures 12' have a particular importance. Lateral supports
can be formed through these projecting portions 11a, which can absorb
transverse forces for example during an offset frontal collision.

[0048] FIG. 7 shows the behavior of the restraint system 8' during impact
upon an obstacle. The left supporting structure 11' is disconnected in
such a manner that it cannot erect any further. The disconnection takes
place as described in FIG. 2b.

[0049] With the embodiments according to FIGS. 6 and 7, the carrier volume
can also be increased by means of the heating element, that is, the
interior pressure can be designed in an incremental manner.

[0050] It should also be pointed out that the embodiments of the restraint
systems are only schematic. It is obvious that very complex supporting
structures can be produced with the teachings according to the invention,
as for example branched tree structures or structures similar to
supporting frames. Branches within the carrier volume are also feasible.

[0051] The arrangement of the supporting structures in cooperation with
the flexible carrier structures, in particular sheets, depends
significantly on the position of the restraint system within the vehicle
and the load conditions to be expected. Thus, the supporting frame
arrangement for a lateral impact protection will be designed in a
different manner due to spatial reasons than supporting structures for
the frontal impact. It is however a fact that a plurality of positions
can be achieved in the vehicle with the longitudinal supporting
structures, which cannot be achieved with conventional gas bags due to
the necessary gas volume.

[0052] The foregoing disclosure has been set forth merely to illustrate
the invention and is not intended to be limiting. Since modifications of
the disclosed embodiments incorporating the spirit and substance of the
invention may occur to persons skilled in the art, the invention should
be construed to include everything within the scope of the appended
claims and equivalents thereof.